1. Field of the Invention
The present invention relates to a catheter for transporting and deploying a stent to treat bifurcation lesions in a branching anatomic duct, and more particularly, to such a catheter having a distal end portion including a catheter body extending to an elongated distal end portion for carrying a stent while guided along a vessel lumen by one of two guide wires a first of which extends to a first branching duct having bifurcation lesions to be treated and the other of the guide wires penetrates a wall of the stent to establish a predetermined distal end portion and predetermined proximal end portion of the stent advanced only along the first guide wire to treat bifurcation lesions of the first branching duct.
2. Description of the Prior Art
Angioplasty is a well-known procedure used to treat atherosclerosis involving the use of a balloon-tipped catheter to treat a narrowed anatomic duct such as a coronary artery. The balloon mounted on the distal end of a catheter is advanced to the narrowed opening in the artery and then the balloon is expanded one or more times to compress arterial plaque and enlarge the narrowed opening. Anatomic ducts treated by angioplasty however can re-close within a short time (referred to as acute re-closure) or again assume a re-narrowing over extended period (referred to as re-stenosis).
Stenting is a technique used to open blocked arteries in patients who have atherosclerosis. The blocked arteries can affect any organ system in the body but are most frequently approached with stenting when the lesion or blockage affects an artery supplying fluid to the heart, brain, kidney or legs.
The installation of a stent initially follows the same procedure involved in an angioplasty of placing a guide-wire across the blockage in the artery and then using the guide wire to advance a balloon dilatation catheter to the site of the blockage whereupon the balloon is inflated to compress plaque and dilate the blockage. A selected stent arranged on a dilation balloon is then advanced along the artery with the aid of the guide wire to a position where stent traverses the site of the blockage. The balloon is inflated to permanently enlarge the stent against the wall of the artery leaving the stent anchored in place. After deflating the balloon and removing of the catheter, the guide wire is removed completing the stent installation procedure. The stent serves as a prop in the artery to help prevent both acute re-closure and to maintain vessel dilation of the treated area of the blood vessel to prevent re-stenosis.
Although stenting a blood vessel is preferred to plain balloon angioplasty in most circumstances, many anatomical situations make it very challenging or impossible to deploy a stent safely. Bifurcation lesion, tortuous blood vessels, ostial lesions and calcified blood vessels are just a few of the very challenging anatomical situations.
Bifurcation lesions are blockages occurring at a branch point of the blood vessel. When only one guide-wire is placed down the blood vessel and used to dilate the vessel at the bifurcation lesion, it is likely that the atherosclerotic material will be forced into the branch of the blood vessel which does not contain the guide-wire and balloon resulting in closing off the unaccessed branch of the blood vessel. This can result in severe damage to the organ supplied with blood by the blood vessel causing a heart attack if the blood circulation is supplied to the heart or a stroke if the blood circulation is supplied to the brain. It is known to simultaneously place a guide-wire down each branch simultaneously and then dilate each branch of a branch duct with a balloon either simultaneously or in at very closely spaced intervals. As long as a guide-wire is maintained across a branch with bifurcation lesions, a balloon catheter can be advanced into that branch even if some previously dilated material from the other branch is squeezed into the branch with lesions. The guide-wire serves as a reliable track providing a pathway for delivering a distal end of a catheter to the branch with lesions at a later point in time. However, it is frequently impossible to place a guide-wire along a side-branch that has been closed-off and, for this reason, two guide-wires are used for treating a bifurcation lesion of a bifurcation vessel.
In the event a stent is advanced into a bifircation lesion after both branches have been dilated, the guide-wire not used for placement the stent must be removed because the guide-wire will become permanently trapped in the wall of the blood vessel when the stent is deployed. However, as pointed out earlier, if the second guide-wire not used for stenting is removed and the stent is deployed using the first guide wire, some of the residue of the atherosclerotic material can be squeezed into the side branch and create a blockage. Even if such a blockage does not occur, maneuvering a guide-wire into the blocked side-branch is difficult because the guide-wire has a tendency to impact and deflect in an unpredictable manner with the struts of the stent adversely affecting steering of the guide wire. The possibility of using a Y-shaped stent was suggested for treating a bifurcation lesion but this stent configuration has an increased bulk adversely affecting upon the success to advance a catheter bearing the stent along a blood vessel to the desired stent deployment site.
Another difficult blockage to approach with a stent is the ostial lesion. This is a blockage occurring at the opening of the blood vessel. Stent deployment has been more successful for treating ostial lesions but still remains challenging because the stent must not overhang in the adjoining vessel and the stent will be of little value if it is placed too far in the vessel obstructed by the ostial lesion. Once a stent is deployed, moving it is impossible.
There are many other anatomic considerations which make stent placement difficult. Tortuous blood vessels are those which have many curves. Stents have a certain degree of stiffness and are sometimes not sufficiently flexible to advance along a course having a very tight curve or multiple soft curves. Other anatomic considerations are calcified blockages which have the characteristic of accumulated calcium in the wall of the blood vessel imparting a very hard bone like physical characteristic to the blood vessel. A calcified blood vessel is difficult or impossible to dilate and treat by balloon angioplasty because of the possibility of tearing of the vessel wall as a result of the increased force needed to dilate the calcified blockage.
It is an object of the present invention to provide safer deployment of a stent for treating bifurcation lesions, tortuous blood vessels, ostial lesions and calcified blood vessels.
It is a further object of the present invention to provide a stent deployment catheter to allow safer and more accurate stent deployment at a predetermined site relative to bifurcation lesions and ostial lesions.
It is another object of the present invention to provide a stent deployment catheter embodying a design and construction of parts to allow the use of one of two guide wires for establishing a length of a distal end portion of a stent for treating a blockage traversed and protectively isolated by the other of the guide wires.